This invention relates to the field of optical waveguides, and more particularly, to the field of machining of optical waveguides using a laser.
Currently, fiber optic technology is used in high speed communication systems. These systems facilitate the communication of video, data, and voice information through vast networks around the globe. Among the components which are used in such systems are various photodetectors which generally receive laser signals from optical fibers, converting them to electrical signals.
In general, photodetectors feature an active area or photo-sensitive surface which reacts to incident radiation, creating a corresponding electrical signal. In a typical configuration, an optical fiber is directed toward the active area of the photodetector so that laser radiation that propagates through the optical fiber falls on the active area. Accordingly, such photodetectors typically include input ports to receive and position optical fibers.
Some photodetectors such as various super high speed photodetectors employ narrow input ports or openings through which to receive the optical fiber. Whereas a typical single mode optical fiber may be 125 microns in diameter, these narrow input ports may range anywhere from approximately 10 microns to 50 microns in diameter. Consequently, there is a need for an optical fiber cable that will fit into such narrow input ports while maintaining proper propagation characteristics.
To address this need, the present invention entails an extended optical fiber having an extended portion and a normal portion. The extended portion is located at an end of the extended optical fiber and has a cladding of reduced diameter in relation with the cladding of the normal portion. A common core runs throughout the normal and extended portions. The thickness of the cladding in the extended portion is sufficient to ensure that the propagation characteristics of the extended optical fiber are unaffected through the extended portion. The extended portion provides the advantage of being easily inserted into a restrictive input port of a photodetector or other device.
The present invention may also be viewed as a method for producing the extended optical fiber. This method includes the steps of focusing a laser on a tangential point of the cladding material of an optical fiber resulting in the tangential ablation of the cladding material. Next, a reduced diameter section is created in the cladding material by rotating the optical fiber under the focus of the laser and moving the optical fiber in a linear direction into the focused laser. Finally, the optical fiber is cleaved at the reduced diameter section, resulting in an extended optical fiber according to the present invention.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims.